Siege of Lunden (886)

The Siege of Lunden occurred in 886 during the Viking invasions of England. The Vikings abandoned London to a Mercian and West Saxon army under Aethelred of Mercia, but they attacked the Anglo-Saxon main camp and captured Aethelred's wife and King Alfred the Great's daughter, Aethelflaed, which they saw as a more important prize.

Background
In 884, a Viking fleet under the brothers Sigefrid and Erik Thurgilsson captured the fortress of Beamfleot before sailing up the River Thames and capturing the Mercian port town of Lunden (London). Afraid that the capture of Lunden would choke off all shipments up the Thames, King Alfred sent 1,000 West Saxon troops to assist Mercia in the recapture of Lunden, something which Aethelred of Mercia's right-hand man Aldhelm conveyed to the Mercian people of Aylesbury as Alfred accepting the Lord of Mercia's demands and being subservient to him. Aethelred, Alfred's son-in-law, decided that Uhtred would attack London from the north gate as he would attack from the marshes with the main army. Uhtred's own plan was ignored, and Aethelred proceeded without caution, leaving his wife Aethelflaed at a camp a mere mile away from the battle.

Battle
Before battle could be joined, the brothers instructed their henchman Tofi to light a black smoke fire from the city center's tower. Uhtred and his men found the north gate to be open, deducing that they were walking into a trap. They walked to the city center, where they found a Mercian shield wall under Aethelred. Aethelred and his men celebrated the capture of the city, and they broke out of their shield wall formation. As the Mercians celebrated, Tofi set a fire in the tower, signalling the Vikings. The Vikings attacked the Anglo-Saxon camp while the main army was in the city, slaughtering the few guards and several civilians there. The Vikings also took Aethelflaed as a captive after she fled into the woods, and Erik decided to take her to Beamfleot.

Aftermath
After the news of Aethelflaed's capture spread, several more men flocked to the brothers' army in Beamfleot, eager for riches and glory. They soon began to raid into Mercia to feed their army, preparing for an invasion of Wessex. Aethelred presented the news to Alfred with a fabricated story, saying that he had killed every Northman in London and taken the city, but at a high cost; in fact, no Northman was killed during the battle, as the city had already been abandoned, and the Danes had withdrawn to Beamfleot. Alfred had his nobles collect their harvests and prepare to raise the fighting men of the fyrd if needed; he was concerned that Aethelflaed, a hostage, would be killed if the Vikings came under attack. Ultimately, Uhtred of Bebbanburg - who was in de facto exile at his estate at Coccham - was recalled, and he made a plan to rescue Aethelflaed from her captivity in Beamfleot.